PDF(Pubmed)
Abstract：
In Saccharomyces cerevisiae, polyadenylated forms of mature (and not precursor) small non-coding RNAs (sncRNAs) those fail to undergo proper 3\'-end maturation are subject to an active degradation by Rrp6p and Rrp47p, which does not require the involvement of core exosome and TRAMP components. In agreement with this finding, Rrp6p/Rrp47p is demonstrated to exist as an exosome-independent complex, which preferentially associates with mature polyadenylated forms of these sncRNAs. Consistent with this observation, a C-terminally truncated version of Rrp6p (Rrp6p-ΔC2) lacking physical association with the core nuclear exosome supports their decay just like its full-length version. Polyadenylation is catalyzed by both the canonical and non-canonical poly(A) polymerases, Pap1p and Trf4p. Analysis of the polyadenylation profiles in WT and rrp6-Δ strains revealed that the majority of the polyadenylation sites correspond to either one to three nucleotides upstream or downstream of their mature ends and their poly(A) tails ranges from 10-15 adenylate residues. Most interestingly, the accumulated polyadenylated snRNAs are functional in the rrp6-Δ strain and are assembled into spliceosomes. Thus, Rrp6p-Rrp47p defines a core nuclear exosome-independent novel RNA turnover system in baker\'s yeast targeting imperfectly processed polyadenylated sncRNAs that accumulate in the absence of Rrp6p.
摘要：
在酿酒酵母中，聚腺苷酸化形式的成熟（而不是前体）小的非编码RNA（sncRNAs）那些未能经历适当的3'-末端成熟的受到Rrp6p和Rrp47p的活性降解，这不需要核心外泌体和TRAMP组件的参与。与这一发现一致，Rrp6p/Rrp47p被证明作为外泌体独立的复合物存在，优先与这些sncRNA的成熟聚腺苷酸化形式结合。与这一观察一致，与核心核外泌体缺乏物理关联的Rrp6p（Rrp6p-ΔC2）的C末端截断版本支持其衰变，就像其全长版本一样。聚腺苷酸化由规范和非规范聚（A）聚合酶催化，Pap1p和Trf4p.对WT和rrp6-Δ菌株中的聚腺苷酸化概况的分析表明，大多数聚腺苷酸化位点对应于其成熟末端上游或下游的一到三个核苷酸，并且它们的聚（A）尾的范围为10-15个腺苷酸残基。最有趣的是，积累的聚腺苷酸化snRNA在rrp6-Δ菌株中具有功能，并组装成剪接体。因此，Rrp6p-Rrp47p定义了面包师酵母中不依赖核心核外泌体的新型RNA周转系统，该系统靶向不完全加工的聚腺苷酸化sncRNAs，该sncRNAs在不存在Rrp6p的情况下积累。
